By lining west facing windows with glass bottles filled with water you can drastically reduce heat gain within your home and cut your need for energy eating artificial cooling systems. The water inside the bottles acts as thermal mass, absorbing and storing incoming heat and then releasing it after the sun has set when you can actually use the warming effect. You can use almost any type of bottle you have around the house, from water bottles to mason jars to really great looking decorative bottles, as long as they’re glass and as long as you like them!